Rice University scientists have 3D printed a lightweight polymer full of holes that’s better than most solid materials at stopping bullets.
The ultra-hard material is a product of a Rice’s Brown School of Engineering study that sought to test polymers based on ‘tubulanes’.
Tubulances are theoretical structures of cross-linked carbon nanotubes thought to have extraordinary strength.
They were first predicted in 1993 by chemist Ray Baughman of the University of Texas at Dallas and physicist Douglas Galvão of the State University of Campinas, Brazil. Both are co-principal investigators on the new paper.
Tubulanes themselves have yet to be made, but their polymer cousins may be the next best thing: Rice’s invention could lead to printed structures of any size with tunable mechanical properties.
Materials scientist Pulickel Ajayan’s lab found that tubulanes can be mimicked as scaled-up, 3D printed polymer blocks that prove to be better at deflecting projectiles than the same material without holes.
According to the scientists, the blocks are also highly compressible without breaking apart.
Lead author Seyed Mohammad Sajadi and his colleagues built computer simulations of various tubulane blocks, printed the designs as macroscale polymers and subjected them to crushing forces and speeding bullets.
The best proved 10 times better at stopping a bullet than a solid block of the same material.
Ajayan’s group made similar structures two years ago when it converted theoretical models of schwarzites into 3D-printed blocks.
The new work is however a step toward what materials scientists consider a holy grail, says Sajadi:
“There are plenty of theoretical systems people cannot synthesize. They’ve remained impractical and elusive.”
“But with 3D printing, we can still take advantage of the predicted mechanical properties because they’re the result of the topology, not the size.”
Tubulane-like structures of metal, ceramic and polymer are only limited by the size of the printer, notes Sajadi.
Optimizing the lattice design could lead to better materials for civil, aerospace, automotive, sports, packaging and biomedical applications.
Image and content: Jeff Fitlow/Rice University